Benzo(a)pyrene (BP) is an environmental chemical carcinogen; the possibility of reducing the harmful effects of BP has been suggested by the observation that certain antioxidants inhibit the carcinogenesis of BP in test animals. It is the purpose of this research to gain a further understanding of the inhibitory effect of antioxidants on the mutagenicity and/or carcinogenicity of BP. The following specific questions are being addressed: (1) Do antioxidants affect the in vitro metabolism or mutagenicity of BP? If so, (2) do different types of antioxidants act similarly or differently, and (3) what specific effects do the antioxidants exhibit and what conclusions can be drawn regarding their mechanism of action? These questions are being investigated by studying the effect of antioxidants on a) the in vitro metabolism of BP and some alkylated derivatives by rat liver microsomes, b) the mutagenicity of BP and derivatives towards the histidine dependent strains of Salmonella typhimurium (the Ames test).